Experiment, or WOCE, the most ambitious
scientific program ever attempted in the
world's oceans. Scientists from 30 countries
conducted intense sea operations, including
more than 500 research cruises, in an effort to
get a picture of global ocean circulation.
"The goal, ultimately, was to help build good
oceanographic data into computer models
designed to depict climate and climate
change," says Lynne Talley, a physical oceanog
rapher at the Scripps Institution of Oceanogra
phy in La Jolla, California, who participated in
WOCE from its beginnings. Over eight years
WOCE measured chemical tracers in the ocean
and collected 20,000 profiles of ocean temper
ature and salinity, which have helped refine
models used for long-term weather forecasts.
Robert Pickart went to sea on WOCE
related cruises eight times in three years, filling
in some of the holes in that map of sea tracks.
A boyish, energetic oceanographer at the
Woods Hole Oceanographic
Institution in Woods Hole,
Massachusetts, and the father
of five small children, Pickart
led a research cruise in the
winter of 1997 to the Labra
dor Sea. A harsh, remote area
in the far northwest corner of
the North Atlantic, the Labra
dor Sea is one of the few
places where conditions are
right to form the young, cold
water that helps drive global
ocean circulation. Here, when
strong westerly winter winds
blow bitterly cold air from
Canada, the chilled surface
waters sink in a process known as deep convec
tion, sending cold water masses through the
deeps and hence to other oceans.
The very conditions that create this
phenomenon-subfreezing temperatures, fre
quent storms, winds gusting to 50 knots
make its observation extremely difficult. "No
one wants to go up there and get pounded,"
says Pickart.
But go Pickart did. For 47 days he and his
team on the R.V. Knorr zigzagged the frigid
waters of the Labrador Sea, dodging giant ice
chunks known as growlers and smaller bergy
bits, looking for places where convection might
be occurring.
Each day Pickart e-mailed his children, at
one point recounting the story of a young
snowy owl that took refuge in the bow of the
ship during a severe storm and the crew's
heroic efforts to save it. "The sun shone only
two days during the whole expedition," Pickart
recalls. "Most days it snowed constantly. Sea
spray froze quickly on the ship's decks, bulk
heads, and bulwarks, building into walls of ice
ten inches thick. The crew members had to
chip away the ice with mallets every few days
so the Knorr wouldn't become dangerously
top-heavy"
Pickart and other scientists suspected that
deep convection was taking place at the edge of
the continental shelf, moving cold water masses
directly into the deep western-boundary
current-a cold limb of the thermohaline
circulation. If they were right, the whole down
stream system of currents would likely feel the
effects of climatic change in the Labrador Sea
much more quickly than scientists had pre
viously suspected. Tethered to the ship with
ropes in driving snow, Pickart and his team
somehow lowered their CTD and other instru
ments into an icy, roiling sea and got the mea
surements they needed to prove their theory.
aCEANOGRAPHY has always suffered
from a plague of undersampling,
in part because of the great diffi
culty and expense of studying the
oceans in remote locations or under stormy
conditions but also because of the limitations
of the tools. Twenty-five years ago most of what
was known about the oceans had been gathered
NATIONAL GEOGRAPHIC, OCTOBER 2000